The present invention disclosed herein relates to an electronic recognition device, and more particularly, to a movement recognizing method of a sensing circuit for recognizing a movement of an object maintained for more than a predetermined time.
An electronic recognition device may include a sensing circuit for recognizing a movement. The sensing circuit recognizes an object as at least one light receiving device receives light (for example, infrared light) emitted from at least one light emitting device and reflected by an object. At least one light receiving device is classified as at least one first direction light receiving device disposed in a first direction and at least one second direction light receiving device disposed in a second direction. The first and second direction light receiving devices convert received light into current signals. The current signals are converted into digital signals by a signal conversion unit.
In order to recognize a direction in which an object moves, the sensing circuit calculates a difference value between first direction digital signals for the first direction light receiving devices and a difference value between second direction digital signals for the second direction light receiving devices. The difference values of the first and second direction digital signals may be expressed as graphs, respectively. A movement direction of an object is determined based on a slope at a zero crossing point of a graph. In more detail, it is determined that the object moves in the direction having a larger slope at a zero crossing point. Additionally, the sensing circuit calculates an average digital signal of digital signals and designates a critical value of the average digital signal. If the magnitude of the average digital signal is greater than the critical value, it is recognized that an object moves. If the magnitude of the average digital signal is less than the critical value, the movement recognizing process of an object is initialized.
The sensing circuit for recognizing such a movement does not reflect noise of a digital signal generated by a movement of an object. Accordingly, noise of a digital signal having a magnitude greater than a critical value is determined as a signal generated from a movement of an object. Due to this, the recognition rate of a sensing circuit is deteriorated. If a filter is used to remove noise of a digital signal, a delay time occurs until the magnitude of a signal is reflected to a result. Accordingly, the fast movement recognition of the sensing circuit is unavailable.